Exercise mask



FIG. 1 is a bottom plan view of an exercise mask showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a left side elevational view thereof;

FIG. 4 is a right side elevational view thereof;

FIG. 5 is a front elevation view thereof;

FIG. 6 is a rear elevation view thereof;

FIG. 7 is a front perspective view thereof; and,

FIG. 8 is a rear perspective view thereof.

The broken lines in the drawings depict portions of the exercise mask that form no part of the claimed design. 

CLAIM The ornamental design for an exercise mask, as shown and described. 